How to download a file on android (Apache Cordova)?

Question

I have created a "backup system", to copy all the table records from a sqlite database, where I take those records and create a .json file. The download in browsers works perfectly, but on android I can't.

#1 - I open a connection to the database.

#2 - Treat errors.

#3 - Give a SELECT on all DB tables.

#4 - Create Backup (agora os registros em .json, Create the file with the database backup)

#5 - Generic utility (convertResults)

// Code to Create Backup
$(document).ready(function() {
    console.log("Application begun")
    var db;

    // → #1 Open connection with the die bank
    db = window.openDatabase("DB_registry", "1.0", "DB_registry", 10485760)

    // → #2 Treat errors
    //Generic error handler
    function dbError(e) {
        console.log("SQL ERROR");
        console.dir(e);
    }
    // → #3 give a SELECT on all DB tables
    function backup(table) {
        var def = new $.Deferred();
        db.readTransaction(function(tx) {
            tx.executeSql("select * from "+table, [], function(tx,results) {
                console.log('↓ SQLResultSetRowList ↓')
                console.log(results)
                var data = convertResults(results)
                def.resolve(data)
            });
        }, dbError);

        return def;
    }
    // → #4 Create Backup
    $(document).on("click", "#doBackupBtn", function(e) {
        e.preventDefault();
        console.log("Begin backup process");
        $.when(
            backup("tb_registry"),
            backup("tb_courses"),
        ).then(function(tb_registry, tb_courses) {
            // console.log("All done")
            //Convert to JSON
            var data = {tb_registry:tb_registry, tb_courses:tb_courses}
            var serializedData = JSON.stringify(data,  null, 2)
            // console.log(serializedData)
            $('#showRegistry').text(serializedData)

            var obj = data
            var data = "text/json;charset=utf-8," + encodeURIComponent(JSON.stringify(obj));

            //!Create the file with the database backup
            var a = document.createElement('a');
            a.href = 'data:' + data;
            a.download = 'data.json';
            a.innerHTML = 'download JSON';

            var container = document.getElementById('container');
            container.appendChild(a);

            })
        })

        //Generic utility
        function convertResults(resultset) {
            var results = []
            for(var i=0,len=resultset.rows.length;i<len;i++) {
                var row = resultset.rows.item(i)
                var result = {}
                for(var key in row) {
                    result[key] = row[key];
                }
                results.push(result);
            }
            return results;
        }


})

Answer 1

This is not possible without cordova-plugin-file! You need to add additional logic for downloading from cordova app into other places, like download folder.